Method and apparatus for making two-coil non-cumulative force spiral springs, and more particularly two-coil non-cumulative force spiral springs having a saddle between the coils



July 4. 1967 J. M. BISHOP AL METHOD AND APPARATUS FOR MAKING TWO- ILNON-CUMULATI FORCE MORE PARTICULARLY TWO-CO1 SPIR SPRINGS AND NO UM TIVEFORCE SPIRAL SPRINGS HAVING ETWEEN THE GOILS 3 Sheets-Sheet l SADDLE BFiled Jan. 12, 1965 F G. 2. u /2 ii "x% z 28 26 a| ao l8 n) u 24 22 I 20FIG. 5.

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INVENTORS JACOB M BISHOP 8:

BY DENNIS D. WESTBROOK OWMW ATTOR NE YS July 4, 1967 J. M. BISHOP ETAL3,329,177 METHOD AND APPARATUS FOR MAKING TWO-COIL NON-CUMULATIVE FORCESPIRAL SPRINGS AND MORE PARTICULARLY TWO-COIL NON-CUMULATIVE FORCESPIRAL SPRINGS HAVING A SADDLE BETWEEN THE COILS Filed Jan. 12, 1965 3Sheets-Sheet 2 F I G. 6.

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44 34 48 40 O a2- 66A ass as g 17 7o 46 42 0 F I G. a. 7 74 72 INVENTORS3 32 JACOB M. BISHOP Bu 1 I BY DENNIS D. WESTBROOK ATTORNEYS 7 7E 10 mw? E 3 L 3 H I AWG m m m w w m C H Y w m R L N N L LMO AI w P C Tw E ETLH R A T W R T IW O E P E Hmw T Sm w B A D R B M N 0 E MRAFL O ,E D .FS .V m IJS 1S A July 4, 1967 METHOD AND APPARATU SPIRAL SPRINGNON-CUMULAT 5 Sheets-Sheet Filed Jan. 12, 1965 FIG. IO.

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K 0 m m I N wwm mm .D m N N GE AD J ATTORNEYS United States Patent3,329,177 METHOD AND APPARATUS FOR MAKING TWO COIL NON CUMULATIVE FORCESPIRAL SPRINGS, AND MORE PARTICU- LARLY TWO COIL NON CUMULATIVE FORCESPIRAL SPRINGS HAVING A SAD- DLE BETWEEN THE COILS Jacob M. Bishop andDennis D. Westbrook, Lansdale, Pa., assignors t0 Ametek, Inc., New York,N.Y., a corporation of Delaware Filed Jan. 12, 1965, Ser. No. 424,929 8Claims. (Cl. 140-89) ABSTRACT OF THE DISCLOSURE The disclosure relatesto forming a two-coil non-cumulative force spring having a saddleportion between the coils which are opposite hand. The spring is formedby a method involving moving an intermediate portion of a length ofspring stock to draw the adjacent portions of the stock over formingedges to sharply bend each of the adjacent portions in order that itwill tend to coil tightly. The adjacent portions are then straightenedor reversely bent to further set them to coil tightly in the originaldirection but on a radius larger than the radius of initial set. Thedisclosed apparatus for carrying out the method involves a punch or thelike for moving the said intermediate portion of the spring stock in astraight line past spaced forming edges and downwardly through anopening wherein the stock is straightened or reversely bent. Springcoiling chambers are provided to permit the coiling up of the saddlespring coils on retraction of the punch. A follower plunger is providedand the contour of the punch and follower plunger can be varied to varythe position of the saddle.

Non-cumulative force spiral springs are well known to the art beingdisclosed in, for example, Lermont Patent No. 2,609,192 and FosterPatent No. 2,609,191. Such springs are widely used commercially, beingsold by the Hunter Spring Division of Ametek, Inc. 'under its trademarkNegator. These springs are known to have a wide variety of usesincluding use as commutator brush springs in rotating electricalmachinery. In the latter use, it has been known heretofore to employ atwo-coil non-cumulative force spiral spring having a saddle between thecoils for engagement of the brush when, in effect, the force of twonon-cumulative force springs is desired. These springs are generallyknown as non-cumulative force saddle springs.

Non-cumulative force saddle springs have heretofore been made by firstforming a single coil non-cumulative force spring by, for example, themethod disclosed in Lermont Patent No. 3,007,239 which issued Nov. 7,1961. The free outer end of the thus formed spring was then coiled untiltwo equal coils were formed. The coils were then separated suflicientlyto permit the formation of a fiat saddle portion employing a punch die.This method involves a large amount of time and handling and hence isvery costly. Further, it makes the achievement of exact resultsdifficult.

In accordance with this invention, .a new method and apparatus forforming non-cumulative force saddle springs is provided with a resultantsimplification in the formation of such springs, greatly increased rateof production and decrease in cost, all with improved accuracy.

The invention and its objects will be further clarified on reading thefollowing description in conjunction with the drawings, in which:

'ice

FIGURE 1 is a front elevation of a non-cumulative force saddle spring;

FIGURE 2 is a front elevation of a second non-cumulative force saddlespring;

FIGURE. 3 is a front elevation of a. third non-cumulative force saddlespring;

FIGURE 4 is a front elevation showing a saddle brush spring structure;

FIGURE 5 is a front elevation partially broken away showing analternative saddle brush spring structure;

FIGURE 6 is a horizontal section through .apparatus in accordance withthe invention;

FIGURE 7 is the horizontal section of FIGURE 6 showing spring stockbeing advanced;

FIGURE 8 is the horizontal section of FIGURE 6 showing the parts of theapparatus in different positions;

FIGURE 9 is the horizontal section of FIGURE 6 showing the parts of theapparatus in different positions;

FIGURE 10 is the horizontal section of FIGURE 6 showing the parts of theapparatus in still different positions;

FIGURE 11 is the horizontal section of FIGURE 6 showing the parts of theapparatus in still different positions; and

FIGURE 12 is the horizontal section of FIGURE 6 showing the par-ts ofthe apparatus in still different positions.

Referring now to FIGURE 1, a non-cumulative force saddle spring 2 has astraight section 4 of spring stock forming a saddle with the remainderof the spring stock being formed into tightly wound spiral coils 6 and8. A second non-cumulative force saddle spring 3 is shown in FIGURE 2.Spring 3 has a straight saddle portion 5 and two tightly wound coils ofspring stock 7 and 9. Spring 3 differs from spring 2 essentially only inthat the straight saddle portion 5 is lower in relation to its coils. Athird non-cumulative force saddle spring 18 is shown in FIG- URE 3.Spring 18 has a straight saddle portion 20 of spring stock being tightlycoiled into coils 22 and 24. Spring 18 differs from spring 3 in thatstraight saddle portion 20 is lower in relation to coils 22 and 24 thanis straight saddle portion 5 with respect to coils 7 and 9.

Referring now to FIGURE 4, saddle spring 2' is shown with coils 6 and 8mounted on rotatable spindles 10 and 12, respectively. Straight saddleportion 4 is shown in engagement with the top of a carbon brush 14.Spindles 10 and 12 are mounted on the body 16.

Referring now to FIGURE 5, saddle spring 2 is shown with the straightsaddle portion 4" in engagement with a carbon brush 26 within acartridge 28. Coils 6" and 8" are in engagement with shoulders 30 and 31respectively of cartridge 28.

The above described springs and their application to commutator brushesare, as indicated previously, well known to the art. For example, seeWelch Patent No. 2,695,968.

Referring now to FIGURE 6, spring forming apparatus 32 has feed rollers34 and 36 for advancing spring stock 38 from a supply not shown.Adjacent the feed rollers 34 and 36 are stock guide members 40 and 42. Acutter 44 cooperates with a pressure pad 46 backed up by a compressioncoil spring 48 to cut off spring stock 38.

A spring forming die 54 has an upper die member 56 with a horizontalopening 58 accommodating a punch 60 provided with a concave face 62. Diemember 66 is spaced from die member 56 by a distance just sufiicientlygreater than the thickness of the spring stock 38 to permit it to travelfreely between die members 56 and 66 and has an opening 68 for theaccommodation of punch 60. Adjacent opening 68, die member 66 has arecessed portion 70 which extends through the bottom of die member 66and isa gravity discharge opening for formed springs. Die mem- 3 her 66has forming edges 66A and 66B on either side of opening 68.

A plunger support member 72 is adjacent recessed portion 70 and has anopening 74 containing a plunger 76 which has a head 77 which is convexto match the concave face 62 of punch 60. Opening 74 is of a width justsufficient to permit free travel of punch 60 and stock 38. Plunger 76 isbacked up by a compression coil spring 78.

A stop member 80 is positioned to limit the travel of spring stock 38 sothat the amount of spring stock between cutter 44 and the center ofpunch 60 will equal the amount of spring stock between the center ofpunch 60 and stop 80. A gap guide 82 is adapted to move upwardly intoopenings 58 and 68 to guide spring stock 38 past openings 58 and 68 andthence move downwardly out of the way of plunger 60. Gap guide 82 isdesirable but not essential.

Operation Assuming the parts of the spring making apparatus 32 to be inthe positions shown in FIGURE 6, spring stock 38 is fed by rollers 34and 36 through stock guide members 40 and 42 and then through diemembers 56 and 66 with gap guide 82 acting to guide the stock 38 as itpasses openings 58 and 68, as illustrated in FIGURE 7 The spring stock38 is advanced until it contacts stop 80 at which point gap guide 82 iswithdrawn and cutter 44 is urged against spring stock 38 which is backedup by pressure pad 46 and spring 48 to sever the spring stock 38, asshown in FIGURE 8.

Punch 60 is now advanced in opening 58 towards spring stock 38 andengages spring stock 38 to move a central portion 58A downwardly throughopening 68 (FIGURE 9) and draw the remainder of the spring stock overforming edges 66A and 66B, respectively, of die member 66 to sharplybend the spring stock on either side of portion 58A to effect an initialset of the spring stock so that the sections of spring stock on eitherside of portion 58A will tend to coil tightly on themselves in oppositedirections, i.e. both outwardly. The portions of thus set stock arestraightened by being moved downwardly through opening 68 which effectsa reverse bending of the material which nevertheless still tends to coilinto two coils, each coil coiling tightly on itself on a radius largerthan the radius of initial set.

Punch 60 is advanced until portion 58A of the spring stock contactsplunger 76 which as the punch continues to advance is forced to move inopening 74 against the force of compression coil spring 78. Theinteraction of concave face 62 of punch 60 and convex head 77 of plunger76 further reverse bends the spring stock at the juncture of the saddleportion 58A and the portions set for coiling to elevate the saddleportion 58A relative to the coils. Punch 60 continues to advance untilall of the spring stock has entered opening 74 as shown in FIGURE 10.

Punch 60 is then withdrawn and is followed by plunger 76 urged by spring78 which backs the spring stock out of opening 74 permitting the ends tocoil as illustrated in FIGURE 11. When coils 58B and 580 have completelycoiled as shown in FIGURE 12, the completed spring will drop downwardlyclear of die member 66 through recessed portion 70.

The center saddle portion 58A of the completed spring ilustrated inFIGURE 1?. lies in a plane passing through the center of coils 58B and58C. Variations in the position of the center saddle portion 58A can beachieved by varying the curvature of the punch 60 and the matingcurvature of plunger 76. The smaller the radius of curvature, the higherthe saddle portion will be relative to the coils. Thus, the springsshown in FIGURES 1 through 3 have saddles made by punches and plungershaving progressively larger radii of curvature. It will also be apparentthat variations in the set of the spring metal stock in being drawnaround forming edges 66A and 6613 can lbe accomplished by varying thewidth of the punch, i.e. the distance the punch is from the formingedges.

Thus, the method of this invention comprises moving a portion of alength of spring stock intermediate the ends thereof to simultaneouslydraw the portions of stock adjacent the intermediate portion overforming edges to sharply bend to a predetermined radius the adjacentportions so that they each tend to coil tightly on themselves. The thusset adjacent portions are then reversely bent to set each adjacentportion so that it still tends to coil tightly on itself in the originaldirection of set, but on a radius larger than the radius of initial set.The adjacent portions are then allowed to coil up.

The specific apparatus and method illustrated in the drawings anddescribed is merely by way of example and is not intended to belimiting.

What is claimed is:

1. The method of forming a two-coil non-cumulative force spring having asaddle portion between the coils of opposite hand comprising moving in asubstantially straight line a portion of a length of spring stockintermediate the ends thereof to simultaneously draw the portions ofstock adjacent the said intermediate portion over forming edges tosharply bend to a predetermined radius said adjacent portions so thatthey each tend to coil tightly on themselves and reverse bending thethus set adjacent portions to set each said adjacent portion so that itstill tends to coil tightly on itself in the original direction of setbut on a radius larger than the radius of initial set and all-owing eachsaid adjacent portion to coil itself up.

2. The method in accordance with claim 1 in which the intermediateportion is urged upwardly after the first mentioned setting operation tofurther reverse bend the stock at the juncture of the adjacent portionsand the intermediate portion.

3. The method of forming a two-coil non-cumulative force spring having:a saddle portion between the coils of opposite hand comprising movingin a substantially straight line a portion of a length of spring stockintermediate the ends thereof to simultaneously draw the portions ofstock adjacent the said intermediate portions over forming edges tosharply bend to a predetermined radius said adjacent portions so thatthey each tend to coil tightly on themselves and straighten the thus setadjacent portions to set each said adjacent portion so that it stilltends to coil tightly on itself in the original direction of set but ona radius larger than the radius of initial set and allowing each saidadjacent portion to coil itself up.

4. The method in accordance with claim 3 in which the intermediateportion is urged upwardly after the first mentioned setting operation tofurther straighten the stock at the juncture of the adjacent portionsand the intermediate portion.

5. Apparatus for forming a non-cumulative force spiral saddle springhaving coils of opposite hand comprising means forming a narrow passagefor a length of spring stock, an opening in said means on one side ofsaid passage, an opening in said means on the other side of said passageopposite the first mentioned opening and providing forming edges, saidmeans having a pair of opposite spring coiling chambers intermediate theends of the second mentioned opening and extending in the direction ofrun of the passage for the spring stock, a punch mounted in the firstmentioned opening to urge an intermediate portion of the spring stockinto the last mentioned opening and draw the stock on either side ofsaid portion over the forming edges to form a tightly wound spring coilon either side of the said intermediate portion of the stock.

6. Apparatus in accordance with claim 5 having means to feed springstock into the passage and means to cut the spring stock to apredetermined length.

7. Apparatus in accordance with claim 5 in which the face of the punchwhich engages the spring stock is concave and in which there is includeda backup plunger opposite the punch and having a convex face registeringwith the concave face of the punch and means to resiliently bias thebackup plunger towards the punch.

8. Apparatus for forming a non-cumulative force spiral spring comprisingdie means having a narrow passage for a length of spring stock, anopening in the die means on one side of the passage, an opening in thedie means on the other side of the passage opposite the first mentionedopening and providing forming edges, ea plunger support adjacent the diemeans and having an opening co-axial with the first mentioned opening, apunch mounted in the first mentioned opening to urge the intermediateportion of the length of spring stock through the second mentionedopening and into the third mentioned opening, a plunger mounted in theopening in the plunger support, and resilient means biasing the plungertowards the punch, said die means having a spring coiling gravitydischarge chamber between the second and third mentioned openings toIeCBiVe the spring on the withdrawal of the punch, a punch mounted inthe first mentioned opening to urge the intermediate portion of thecut-oh. length of spring stock through the second mentioned opening andinto the third mentioned opening.

References Cited UNITED STATES PATENTS 443,256 12/1890 Logan 29-173 X2,143,429 1/1939 Auble 72-351 X 2,223,321 11/1940 Kempe.

2,269,313 1/1942 Klocke 72351 X 2,348,871 5/1944 Wiley 18-19 2,602,4117/ 1952 Schnell.

3,203,218 8/1965 Bolt et a1. 18-19 X WILLIAM J. STEPHENSON, PrimaryExaminer.

1. THE METHOD OF FORMING A TWO-COIL NON-CUMULATIVE FORCE SPRING HAVING ASADDLE PORTION BETWEEN THE COILS OF OPPOSITE HAND COMPRISING MOVING IN ASUBSTANTIALLY STRAIGHT LINE A PORTION OF A LENGTH OF SPRING STOCKINTERMEDIATE THE ENDS THEREOF TO SIMULTANEOUSLY DRAW THE PORTIONS OFSTOCK ADJACENT THE SAID INTERMEDIATE PORTION OVER FORMING EDGES TOSHARPLY BEND TO A PREDETERMINED RADIUS SAID ADJACENT PORTIONS SO THATTHEY EACH TEND TO COIL TIGHTLY ON THEMSELVES AND REVERSE BENDING THETHUS SET